Apparatus for the electrolytic production of high-purity iron



June 29, 1965 F. E. SMITH 3,192,145

APPARATUS FOR THE ELECTROLYTIC PRODUCTION OF HIGH-PURITY IRON Original Filed Sept. 17, 1959 5 Sheets-Sheet 2 Ff qi INVENTOR. FRANK E. SMITH BY 5% w/Qdw e June 29, 1965 APPARATUS FOR THE ELECTROLYTIC PRODUCTION OF HIGH-PURI-TY IRON F- E. SMITH Original Filed Sept. 17-, 1959 3 Sheets-Sheet 3 six ATTORNEYS United States Patent 3,192,145 APPARATUS FOR THE ELECTROLYTIC PRO- DUCTION OF HIGH-PURI'IY IRGN Frank E. Smith, 2016 Belle Ave, Lakewood, Qhio Original application Sept. 17, 1959, Ser. No. 840,712, new Patent No. 3,118,826, dated Jan. 21, 1964. Divided and this application .iuly 17, 1951, Ser. No. 124,722 22 Claims. (Cl. 294-234) This application is a division of my copending patent application Serial No. 840,712, filed September 17, 1959, now US. Patent No. 3,118,826, and said application, as originally filed, forms a part or" this disclosure and is incorporated herein by reference.

This invention relates to process and apparatus for the electrolytic production of high-purity iron.

It is the principal object of the invention to provide a process which enables the production of high-purity iron from low-grade or impure metal, such as pig iron, and at a cost comparable with present-day production of iron and steel from converters and open hearth furnaces.

A further object of the invention is to provide a process of, and apparatus for refining impure iron, to replace open hearth procedures presently used.

Another object is to provide a process and apparatus by which high-purity iron may be produced electrolytically in large quantities through the use of electrodes having flat faces reciprocally varying in thickness during a run so that the preset spacing of the faces remains substantially constant.

A still further object is to provide an electrolytic cell in which circulation of fresh electrolyte across and between confronting faces of the electrodes is even and uniform throughout the length and height of the electrodes.

Another object is to provide an economical and eflicient electrolytic cell as aforesaid, in which the electrolyte is cleansed of sediment and impurities, renewed and cooled outside the electrolytic zone, then recirculated across and between electrodes.

Yet another object is to provide a cell construction which enables anode-cathode pairs to be made up before introduction into the cell and then loaded thereinto with a minimum loss of time, so that almost continuous pro duction of the cell may be maintained throughout its life.

Another object is to provide a process by which highpurity iron may be produced in large quantities for the precise control and output of alloys and at costs comparable to those of prior art methods.

Other objects and advantages of the invention will become apparent to those skilled in the art, after a study of the following description in connection with the accompanying drawing.

In the drawings:

FIGURE 1 is a central'vertical cross section through one of the cells embodying the invention;

FIGURE 2 is a horizontal cross section taken in a plane identified by line 22, FIGURE 1;

FIGURE 3 is a horizontal cross section taken in a plane identified by line 33, FIGURE 1, parts being broken away for greater clarity of illustration;

FIGURE 4 is a detail view to a reduced scale, showing the manner in which the electrodes reciprocally vary in thickness during the operation of a cell;

FIGURE 5 is a vertical cross sectional view taken in a plane identified by line 5-5, FIGURE 6, and showing a modified form of cell construction; and

FIGURE 6 is a vertical cross sectional View taken in a plane identified by line 6-6, FIGURE 5.

Referring in detail to the drawings, 1 identifies a foundation on which rest a plurality of beams 2 in spaced parallel relation and supporting the circular metal bottom plate 3 of the cell. As shown upon FIGURE 1, the cylindrical 3,192,145 Patented .iune 29, 1955 wall 4 of the cell encompasses and extends below bottom plate 3 to rest upon a metal ring 5, so that the weight of the cell wall and parts carried thereby is transmitted directly to the foundation.

The metallic bottom and walls of the cell are protected by a lining 6, of concrete. A horizontal partition generally indicated at 7 is conveniently cast integral with lining 6 to provide a planar upper face. The partition is r enforced by a pair of I-beams 8 and 9 extending between opposite portions of the side wall, in spaced parallel relation and equally spaced from and upon opposite sides of their parallel diameter. These beams are embedded in concrete trusses which, as shown upon FIGURE 1, are shaped to provide spaced parallel confronting ledges 7a and 7b, defining between them a central diametral open ing for circulation of the electrolyte as subsequently described. As best shown upon FIGURE 3, the two segment-shaped portions of the partition are provided, respectively, with rectangular openings 16 and 11 to provide return circulation of the electrolyte. Reenforced, spaced, parallel beams 12 and 13 at the top of the tank are conveniently cast integral with it. Each is directly over a corresponding one of the rcenforcernents S and 9, with their top surfaces coplanar with the top rim of the tank. This rim includes an angle ring 14 welded or riveted flush with the top edge of the tank wall. A flat circular cover 15 of concrete has a central opening 16 disposed over the corresponding opening in partition 7. Opening 16 is sized for convenient insertion and removal of the electrode pairs.

A removable superstructure generally identified at 17, FIGURE 1, rests upon cover 15 over opening 16 and protects the bus bars subsequently described. This superstructure which may be of wood, includes parallel side walls 18 and 19 connected by arcu-ate end walls 20 and 21 and a top 22, provided with an inspection opening 23 and a hinged lid 24. As best shown upon FIGURE 2, the end walls 20 and 21 follow the curvature of top or cover 15 and have openings such as 25, 26, FIGURE 2, for bus bars 27, 28 which for convenience will be taken as positive and negative, respectively. Where a number of these cell units are in side-by-side position, the bus bars may run from one to the next, as indicated at 2711, FIGURE 2. Each bus bar is shown to consist of a pair of copper straps supported at each end by insulators Z9 and 36 mounted on cover 15 and having upstanding projections between and fixed to the straps. A switch 23a is open when the cell is operating and closed to cut it off the line.

FIGURES l and 3 show anode A and cathode C as they exist at the beginning of a run or cycle. The anode consists of a slab of impure iron to be refined, such as pig iron, and may be twelve inches or more in thickness, while the cathode consists of a relatively thin slab of highpurity iron. From FIGURES 1 and 3 it will be noted that anode and cathode have the same dimensions in the vertical direction and in the horizontal direction parallel with the bus bars. It will also be noted that the electrodes are supported on and along the respective ledges 7a and 7b of partition '7, with small overlap at their ends. Thus they are supported in erect position over the central opening in the partition, with their confronting faces parallel and closely spaced by from one and one-half to onequarter of an inch as determined by conditions subse quently explained. There is thus defined between the electrodes a uniform flow space 31 for electrolyte E.

Each electrode has welded to its back vertical surface, a plurality of yokes 32. Comparing FIGURES 1 and 2,

it will be noted that each electrode is provided with four vertical rows of these yokes evenly spaced in the horizontal direction, each row comprising a vertical column or series of four yokes, also uniformly spaced. A ribbon or strap of copper, such as 33, extends from the level of the bus bars, downwardly through each respective vertical column of yokes and is held in flat contact with its electrode by set screws 34 threaded into and through the yokes. Two set screws are shown for each yoke. See FIGURE 3. In this way a precise and uniform distribution of current is effected over the faces of the electrodes. Each strap 33 is, protected from stray currents by a covering of insulating paint except over its contact and confronting face areas, and is connected with its bus by Z-connectors such as 35 and 36. Thus, for example, each anode strap 33 has a connector 35 with one offset end fixed thereto and its other end attached to the respective bus bar. The connectors 36 between cathode bus bar- 28 and its drop copper are esentially like those described for the anode but are shorter than connectors 35 because of the closer proximity of bus 28 to the contiguous edge of opening 16. To reduce by-passing of current, a sheath 33a of insulating or di-electric material such as micarta or asbestos board, is provided to contact or rest upon the electrodes and to extend to a level a little above the highest level attained by the electrolyte during a cycle of operation. Conveniently this sheath may be in the form of a unitary insert or as separable sheets. In either event, as shown upon FIGURE 3, its ends project beyond its sides into substantial contact with abutments 6a of the tank lining to be thereby held in fixed position. Also, as shown in FIGURE 6, end plates 33b extend downwardly over the entire end areas of the electrodes to thereby close the electrode zone from stray currents.

. The partition 7 generally divides the tank into communicating upper and lower compartments. The upper compartment is, in turn, divided into three distinct chambers or sections, by removable panels 37 and 38 extending vertically between beams 12 and 13, respectively, and partition 7. Thus, referring to FIGURE 1, panel 37 has a Z-bar 39 secured to and along its upper edge to fit smoothly about the adjacent corner of beam 12.:

The lower edge of the panel has an angle bar 4% fixed therealong to rest upon the partition. Thus the panel with its bars may be removed by sliding it inwardly and upwardly. The panel 38 at the cathode side of the cell is essentially an allochiral duplicate of panel 37, so that it'is suflicient-to identify angle bars 41 and 42' secured to and along the upper and lower edges, respectively, of the panel. Alternatively, the panels 37 and 38 alone may be removable, with angles such as 39 and 40 fixed in position. In either case the panels divide the upper compartment of the tank into three sections, namely, a central or electrode section and two segmental-shaped sections on either, side of the central section which, as subsequently explained, are for the conditioning of the electrolyte.

Circulating pumps 43 and 44 are mounted on opposite sides of cover 15. Pump 43 is provided with driving motor 45,.intake. pipe 46 extending downwardly into the left chamber or section, as the parts are viewed upon FIGURE 1, and discharge pipe 47 extending into the central chamber or'section. Since the two pump units are preferably duplicates, it is sufficient, referring to pump 44, to identify its driving motor 48, intake pipe 49 and discharge pipe 50. From FIGURE 2 it is noted that the discharge pipes 47 and 50 enter the centralsection at discrete locations spaced therealong to assure an even flow and supply of fresh electrolyte.

As indicated by the arrows of FIGURE 1, operation of. the pumps induces flow of electrolyte downwardly through the central section, across and between the confronting faces of the electrodes, thence upwardly through openings and 11 inpartition 7, back to the side sections previously identified. Cooling coils 51 and 52 are positioned just above the openings and are connected with a source of coolant, circulating and control means, not shown. The circulation of coolant may be under control of valves, not shown, thermostatically operated in reat. sponse to small temperature changes of theelectrolyte, to etiect a close and precise control of temperature. Such valves, which are well known in the art, are settable for any selected value over a suitable range of temperatures.

Two baskets or containers 53 and 54 having grilled or foraminous sides and bottoms are shaped to correspond with openings 10 and 11, respectively, and sized to rest upon the edges thereof, as will be clear from inspection of FIGURES 1 and 3. For a purpose to be subsequently described, these baskets are filled with finely divided steel and are easily removable for that purpose.

The lower portion of the tank or cell forms a settling chamber for sludge released from the anode. To remove this sludge as conditions require during acycle of operation, I provide a screw conveyor 55 extending diametrically across the bottom of the tank. and driven, in a way obvious from inspection of FIGURE 1, by. a belt 57 and motor 56 mounted upon a bracket 58 fixed to one of a plurality of vertical reenforcing beams 59. As shown upon FIGURE 3 there are six of these beams at equallyspaced intervals about the periphery of the tank. Each beam rests upon ring 5 and extends upwardly to a level short of the top of the tank. The sludge is discharged through a downspout 60 under control of a valve 61.

Coils 62 are provided near the bottom of the lower chamber and connected with a source of heating medium and control valves, not shown, so that the electrolyte may be maintained at optimum operating temperature during change-over, repairs or adjustments, and also quickly brought to operating temperature when first being placed on the line or after a considerable period of shut-down. Electrically-energized heating coils or means may be substituted for coils 62. As indicated at 63, FIGURE 1, the bottom of the tank is formed of two half-sections sloping upwardly from a common diametral line defined by conveyor 55. That is, the bottom of the tank is V- shaped in cross section :in a vertical plane normal to the plane of FIGURE 1, so that impurities settling out from the anode, gravitate to the, conveyor. At 64 there is shown a pipe by which. electrolyte may be drawn down to about the level indicated at 65 when the cell is to be charged with new electrodes.

In the modified construction shown upon FIGURES 5 and 6, the draw-downpipe 64 and its associated pumping mechanism,-not shown, are not required. In the form of the invention shown in these figures the tank 4 and concrete lining may be in the same :form as shown upon FIGURES 1 to 3. However, in the modification being described, ledges 7a and 7b of partition 7 are omitted.

. A removable support or cage for the electrodes consists of a base 66 of concrete of open rectangular shape with internal dimensions about the same as those of the central opening in partition 7 and provided with'reenforcing channels 67 and 68:in its side members. These side members are integrally connected by uniformly spaced cross bars 69 having their upper edges beveled as indicated at 69a, FIGURE 6, and reenforced by channels 76, to define circulating ports between them.

A plurality of lifting straps 71 are provided, three being used on each side in the model illustrated. Each strap may be welded or otherwise rigidly attached to the fiat base of its channel, to extend upwardly to a level above the electrodes A and C which rest upon and are supported by base 66. Referring to FIGURE 6, it will be noted that each strap 71 has a lifting eye 72 in its top end. The straps are uniformly spaced in parallel vertical positions along each side of the base and are so located that each lies between and in oifset relation with two adjacent copper lead-ins 33, as described in connection with FIGURES 1, 2 and 3. It will be understood'that these leads may be connected with the electrodes in the maner previously described.

With the modified construction, a frame 66 may be loaded with a pair of electrodes outside the tank then lifted by a crane by means of straps 71 and positioned within the tank, with base d6 resting upon partition 7, as depicted upon FIGURE 5.

By the use of the construction shown upon FIGURES 5 and 6, it is possible to maintain a cell in almost continuous production since only a few minutes are required to withdraw a pair of electrodes, that is, an eroded anode and a full cathode of high-purity iron, install a new pair as in FIGURES 1 and 5 and start a new cycle of production.

Operation Inoperation a unit is loaded with an anode in the form of a relatively thick slab of iron to be refined, such as pig iron. These slabs may be cast directly from a blast furnace. At the start the anode may, in the form shown, have a thickness of a foot or more. The cathode is a slab of high-purity iron having a thickness of about one inch. The fiat parallel confronting faces of the electrodes may have a spacing of from one-quarter to one and one-half inches, depending upon the smoothness of the electrode faces. That is to say, the spacing will be a minimum where the confronting faces are smooth, and greater with increasing roughness or irregularities of these faces.

The electrolyte is an aqueous solution of ferrous chloride having a concentration of from 1 to 8 pounds per ten pounds of water and a pH of between 5 and 8. By the control of fluid to and through coils 51 and 52, the temperature is maintained between 65 and 80 C. The current density may have any value between 1 and 6 amperes per square inch. However, since the time required for a cycle will be in inverseproportion to the current density, the maximum practical density is preferred.

The voltage for operation is as follows:

Volts To convert Fe++ to Fe +0.44l To convert Cl to Cl l.358

Total 1.799

Bath resistance (approximate):

/4" spacing +0.40 1" spacing +1.50

1 /2 spacing +2.25

Bath resistance varies with the current density, that is,

amperes per square inch per inch. As an example,

l" 0.25 ohms 6 amperes/ sq. in. resistivity of the bath per square inch per inch of length.

The pumps 44 and 45 are selected to induce a fiow between electrodes of from 5 to 40 feet per minute. Due to the relatively large capacity of the pumps and the spacing of their discharge pipes in and along the electrode chamber, a smooth and uniform fiow between electrodes is continuously maintained, thereby assisting in an even erosion of the anode face and a corresponding uniform accretion of high-purity iron at the cathode. This function is enhanced by the fact that the level of electrolyte over the electrodes is maintained a substantial distance above them so that turbulence of liquid flow between them is negligible. A

As indicated by the arrows upon FIGURE 1, the flow of electrolyte is -downwardly between electrode faces, through the central opening in partition '7', to the lower chamber. In this chamber the flow divides, half of the electrolyte moving upwardly through opening 10 and half through opening 11. Due to the much greater flow area provided as the electrolyte emerges downwardly from the central electrode chamber, its velocity decreases to provide plenty of time for impurities to settle to the bottom of the tank. This function is augmented by the change to an upward direction of flow as the electrolyte begins to move upwardly to the side sections of the upper chamber.

During its passage between electrodes, the electrolyte provides a continuously renewed solution of ferrous chloride. At the same time it acts to maintain a uniform temperature of the electrodes and to wash down impurities released from the anode as it is gradually eroded.

As the electrolyte passes into the electrode zone, the ferrous ions (Pe++) migrate to the cathode and the chlorine ions (01-) migrate to the anode. As the ferrous ions contact the cathode and lose their charge, they become a part thereof. The chlorine ions, in contacting the anode are converted to atomic chlorine and immediately react with the iron of the anode to form more ferrous chloride, so that the concentration of ferrous chloride is maintained. Any ferric chloride in the solution is converted to ferrous form as the electrolyte moves upwardly through the mass of finely divided steel in baskets 53 and $4, as previously described.

As the anode is eroded the impurities therein are washed downwardly by the continuous even flow of electrolyte across and between the electrode faces and settle to the bottom of the tank where they are removed by conveyor 55. The conveyor may be run intermittently or continuously as conditions and rate of production require.

A very close control of temperature within the range previously specified, is afforded by coils 51 and 52 because the electrolyte .is continuously recirculated over and about them at a greatly reduced velocity over that between electrodes. Ample time is thereby afforded for heat exchange from the electrolyte to the coolant in the coils. Since cooling is effected after the solution has passed through the finely divided steel in baskets 53 and 54, a maximum rate of conversion of ferric to ferrous chloride is assured.

In the form of electrode supporting means shown upon FTGURES 5 and 6, anode-cathode pairs, together with their pallet as are made up in advance, ready for insertion into a cell. Reloading of a cell may be effected in a matter of minutes so that each cell may be kept in production substantially continuously. The high-purity iron of the cathode is essentially free of sulphur, manganese, phosphorous, iron oxides, carbon, silica and gases such as hydrogen and nitrogen. Being highly resistant to atmospheric corrosion, it finds many uses as it comes from the cell, for example in water piping, screens, railings and fences. It is a superior product for transformer cores, motors and electronic applications. The high-purity iron produced by my invention may be used for containers, without tin plating, for non-acid substances such as oil; and it can be produced at lower cost than the tin plate conventionally used for such materials. It is a superior material for automobile bodies because corrosion will not occur under the finish nor on the inside surfaces, so that undercoating is not required. Furthermore, it is superior as a base for chromium plating since it avoids the penetration of rust commonly encountered at present.

FIGURE 4 shows the electrodes as they exist when a run is about half completed and it will be noted that the spacing between the electrodes remains substantially constant throughout the run. This is important because it enables the conditions of voltage, current density, tem perature and rate of circulation of electrolyte to be maintained uniform or varied in a precise predetermined way during the run, thus resulting in a high-purity iron uniform in composition for alloying with carbon, nickel, chromium, molybdenum, tungsten and other known elements and compositions. Since the slabs produced are extremely pure, a very close and precise control in the production of alloy steels is possible. Alloys so produced are superior to those produced by the vacuum melting process currently used.

While I have disclosed the form of process and apparatus presently preferred by me, numerous modifications and substitutions of equivalents are possible and will occur to those skilled in the art after a study of the fore areas is going disclosure. For example, I may substitute a bath of ferrous bromide for the ferrous chloride bath previously described,,and in about the same concentration. Or, alternatively, I may use ferrous bromide as an additive to the ferrous chloride, in the ratio of about four pounds of FeCl 'plus three pounds of FeBrto ten pounds of water. In cases where, due to inadvertence or lack of proper control of the variables of temperature, rate of circulation of the electrolyte and current density, the anode face becomes rough, uneven or pitted, it will be withdrawn from the bath and reconditioned by grinding or machining its face to restore it to clean smooth face. Of course such a procedure need not delay production since a new pair of electrodes may be inserted into the cell in a few moments and the used ones smoothed and later replaced into the cell. Therefore, this disclosure should be taken in an illustrative rather than a limiting sense; and it is my desire and intention to reserve all modifications of process and apparatus within the scope of the subjoined claims.

What is claimed is:

1. In an electrolytic cell for the production of highpurity iron, a tank, first'pa-rtition means dividing said tank into upper and lower compartments, second partition mean-s dividing said upper compartment into laterallyspaced first and second sections, electrodes in said first section, means to connect said lower compartment with each of said first and second sections, and means operable to controllably and positively circulate electrolyte from said lower compartment upwardly through said second section, then downwardly through said first section and between the electrodes therein.

2. In an electrolytic cell for the production of highpuri-ty iron, a tank, partition means in said tank dividing the same into an upper and a lower compartment, means in said-upper compartment defining first and second chambers, means supporting a pair of electrodes in closclyspaced relation within said first chamber, and means operable to positively and uniformly circulate electrolyte between the spaced faces of the electrodes, to said lower compartment and said second chamber in succession.

6. An electrolytic cell as in claim 2, comprising a foraminous container means supported across said secforaminous container means.

4. An electrolytic cell for the production of high-purity I iron comprising, a tank, a first partition means dividing said tank into upper and lower compartments, removable panel means in said upper compartment dividing the same into laterally-spaced first and second sections, a pair of electrodes in said first section with parallel, closely-spaced, vertical confronting faces, passage means in said first partition means connecting-the lower compartment with the upper, and pump means operable to continuously and controllably circulate electrolyte from said lower compartment, upwardly through said second section then downwardly through said first section whereby said electrolyte passes over and between the confronting faces of said electrodes and into said lower. compartment.

5. An electrolytic cell for the production of high-purity iron comprising a tank, a partition dividingsaid tank into upper and lower compartments, a pair of spaced parallel generally-vertical panels positioned in said upper compartment and dividing the same into a central section and two side sections, there being apertures in said partition into each said section, pump means operable to continuously and controllably circulate electrolyte from said lower compartment, upwardly into each said side section thence into said central section and downwardly to said lower compartment.

6. An electrolytic cell as in claim 5, and foraminous container means for finely divided steel, supported on said partition over at least one aperture therein.

7. In an electrolytic cell for the production of high.-

purity iron, a tank having a partition between its top and bottom and dividing the same into upper and lower compartments, said partition having a central aperture therein, a pair of electrodes supported by said partition over said aperture with closely-spaced confronting faces, a plurality of copper straps each secured to the back face of a respective electrode in vertical, spaced relation therealong, a pair of bus bars fixed with the top of said tank in spaced parallel relation, and a connector bar from each strap to a respective one of said bus bars.

8. In an electrode unit for the production of high-purity iron, a grilled supporting pallet, a'pair of electrodes sup ported on said pallet with their flat confronting faces slightly spaced, a plurality of copper straps secured in vertical, horizontal-spaced relation, to the back of each said electrode and extending upwardly therefrom, and a plurality of lifting straps having their lower ends attached to said pallet and extending upwardly in horizontally-spaced relation.

9. Anelectrode unit as in claim 7, the anode of said pair comprising a slab of impure iron and the cathode thereof comprising a slab of high-purity iron, the dimensions of said anode and cathode in the direction normal to their confronting faces having a ratio of about 12:1, respectively.

14). An electrolytic cell' for the production of highpurity iron comprising a tank, a partition dividing said tank into upper and lower compartments, means for dividing said upper compartment into a first and a second section, means in the first-section of the cell for supporting electrodes, electrodes supported thereby with their faces opposed and spaced apart from each other, said partition having a passage in alignment with said electrodes and another passage aligned with the second section, and

means to continuously circulate electrolyte upwardly from said lower compartment through said second section and downwardly through said first section and said passage.

11. An electrolytic cell as defined in claim 10 comprising electrolyte purifying means extending across the broad-extent of said second section and through which said electrolyte passes.

12. An electrolytic cell as defined in claim 10 comprising means to reduce turbulence in the flow of electrolyte through said first section.

13. An electrolytic cell having upper and lower chambers for electrolyte, a throat connecting the two chambers comprising a narrow slot with electrodes for walls, said electrodes having broad, parallel, congruent faces, means to supply the electrodes with electrolytic current, and means to transfer electrolyte from the lower to the upper chamber and back to the lower chamber at a rate which generates a flow of several feet per minute through the slot.

14. The apparatus of claim 13, including a foraminous support for a reactive substance located in the flow of spent electrolyte from the electrodes, and means to constrain the spent electrolyte to How through said foraminous support.

15. An electrolytic cell comprising block iron electrodes having plane faces of equal size, means to support the electrodes with faces opposed and forming a narrow, unobstructed passage between the electrodes, meansto continuously flow iron salt solution evenly between and parallel to the faces from one edge to the opposite edge of the electrodes whereby the said opposed faces of both electrodes are continuously and equally swept by a current of moving electrolyte adequate to remove detritus from the faces of the electrodes, means-to flow electric current between the electrodes through and transverse to the current of the continuously moving electrolyte to deposit iron on one of the electrodes and to dissolve it from the other, means to return electrolyte from the said opposite edge to the said one edge, and means in the means to return to reduce iron salts in the electrolyte.

16. An electrolytic cell for the refining oflow grade iron which comprises a container adapted to hold a solu tion of electrolyte and to submerge the electrodes, upper and lower chambers in said container and an electrode section therebetween, a large electrode of low grade iron and a small electrode of relatively pure iron in the electrode section spaced to provide a submerged, narrow channel connecting the chambers, means to continuously flow the electrolyte into one of the chambers and through the nar row channel parallel to both electrodes and at equal velocity with respect thereto, regenerating means, means to flow electrolyte from the chamber downstream of the electrodes, through said regenerating means, and means to flow electrolyte from the regenerating means to the chamber upstream of the electrode section.

17. An electrolytic cell having a plurality of chambers which are interconnected by slot means the walls of which comprise electrodes, current supply means connected to the electrodes, said electrodes adapted to be below the level of the electrolyte in the cell, means to circulate electrolyte from one chamber through the slot means over the surfaces of the electrodes to the other chamber and back to said one chamber, and electrolyte regenerating means, in the course of the circulating electrolyte, through which the spent electrolyte from the electrodes passes.

18. The apparatus of claim 17 in which the chambers and slot are vertically aligned.

19. The apparatus of claim 17 including heat exchanger means between the slot and the regenerating means.

20. The apparatus of claim 17 including heat exchanger means between the regenerating means and the slot.

21. The apparatus of claim 17 including sump means downstream from the slot and means to extract detritus therefrom.

22. The apparatus of claim 17 in which the circulating means includes pump means which have a capacity sufficient to sweep the faces of the electrodes in the slot with electrolyte at a velocity of about 5 to ft. per minute.

References Cited by the Examiner UNITED STATES PATENTS 505,895 10/93 Cutten 204-234 780,191 1/05 Johnson 204--113 1,945,107 1/34 Cain 204113 2,494,264 1/ Ryman 204-239 2,538,991 1/51 Trask 204-113 JOHN H. MACK, Primary Examiner.

JOHN R. SPECK, Examiner. 

2. IN AN ELECTROLYTIC CELL FOR THE PRODUCTION OF HIGHPURITY IRON, A TANK, PARTITION MEANS IN SAID TANK DIVIDING THE SAME INTO AN UPPER AND A LOWER COMPARTMENT, MEANS IN SAID UPPER COMPARTMENT DEFINING FIRST AND SECOND CHAMBERS, MEANS SUPPORTING A PAIR OF ELECTRODES IN CLOSELY-SPACED RELATION WITHIN SAID FIRST CHAMBER, AND MEANS OPERABLE TO POSITIVELY AND UNIFORMLY CIRCULATE ELECTROLYTE BETWEEN THE SPACED FACES OF THE ELECTRODES, TO SAID LOWER COMPARTMENT AND SAID SECOND CHAMBER IN SUCCESSION.
 5. AN ELECTROLYTIC CELL FOR THE PRODUCTION OF HIGH-PURITY IRON COMPRISING A TANK, A PARTITION DIVIDING SAID TANK INTO UPPER AND LOWER COMPARTMENTS, A PAIR OF SPACED PARALLEL GENERALLY-VERTICAL PANELS POSITIONED IN SAID UPPER COMPARTMENT AND DIVIDING THE SAME INTO A CENTRAL SECTION AND TWO SIDE SECTIONS, THERE BEING APERTURES IN SAID PARTITION INTO EACH SAID SECTION, PUMP MEANS OPERABLE TO CONTINUOUSLY AND CONTROLLABLY CIRCULATE ELECTROLYTE FROM SAID LOWER COMPARTMENT, UPWARDLY INTO EACH SAID SIDE SECTION THENCE INTO SAID CENTRAL SECTION AND DOWNWARDLY TO SAID LOWER COMPARTMENT. 